Electromagnetic audible-signal device



NOV. 2, 1948. POOLE 2,452,678

ELECTROMAGNETIC AUDIBLE-SIGNAL DEVICE Filed Sept. 2'7, 1945 //Vl/NTO ARTHUR B. P0 00. E

Patented Nov. 2, 1948 iJNl'lED STATEAS FATENT @ZFFIQE Arthur B. Poole, Harwinton, Conn.

Application September 2'7, 1945, Serial N0. 618,866

4 Claims.

v The present invention relates to improvements in electromagnetic audiblasignal devices and relates more particularly to devices of the character referred to which are especially suitable for use in electric clocks.

One of the objects of the present invention is to provide a superior electromagnetic audible-signal device having a compact and low-cost construction and arrangement of parts.

Another object of the present invention is to provide an audible-signal device of the character referred to comprising an electromagnet and a cooperating armature and in which the, magnetic flux of the said electromagnet acts to cushion the movement of the said armature, in addition to attracting the same.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art and which are not claimed in any separate application.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a broken view in front elevation of one form of electromagnetic audible-signal device embodying the present invention;

Fig. 2 is a sectional View thereof taken on the line 2--2 of Fig. 3, but on the same scale as Fig. 1;

Fig. 3 is a sectional view taken on the line 33 of Fig. 1 but on a larger scale;

Fig. 4 is a perspective View of the electromagnet-unit, detached; and

Fig. 5 is a perspective View of the armature, detached.

The particular embodiment of the present invention shown in the accompanying drawings and chosen for purposes of making clear the principles of the present invention, includes an electromagnet comprising a cup-shaped shell l8 which includes a cylindrically-contoured lateral wall I I and an end wall It integral with the said lateral wall.

Integral with and projecting forwardly from the lateral wall H of the shell It are two polesalients i3 and I4 located diametrically opposite each other and respectively adapted to project forwardly through arcuate slots I5 and I8, which latter extend from front to rear through a mountlug-plate ll.

Located within the shell I0 is a spool 89 upon which is wound an energizing-coil Ell. Extending azrially through the spool l9 and hence also passing axially through the energizing-coil 29 and shell ll], is a core 2! having its forward end extended through a circular clearance-opening 22 formed in the mounting-plate 5 l at a point midway between the arcuate slots 15 and IS therein.

Rigidly secured to the forward portion of the core 21 is a plate-like flux-shunting member 23 adapted'to shunt magnetic flux between the polesalients i3 and Id of the shell [6 and the said core 2 l. The said flux-shunting plate is not per se caimed herein but is included in the subject matter of my copending application filed on even date herewith and now issued as Patent No.

Forwardly of the flux-shunting member 23, the core 2i is formed with a relatively-slender neck 2% terminating in a disk-like head 25. The said head normally projects part way into an aperture 28 formed centrally in a plate-like armature 21, as is especially Well shown in Fig. 5.

ihe armature 2! above referred to is so sized as. to freely fit in the space between the pole-salients l3 and M of the shell I0 and is secured in rearwardly-spaced relationship to a spring-like armature-arm 28 by means of studs 29-49. The. upper end of the armature-arm 28 is secured in forwardly-spaced relationship with respect to the mounting-plate l! by means of a stud 39, as is especially well shown in Fig. 3.

The parts IE), 2!, 23 and 21 are formed of soft iron or other suitable magnetic material, while the parts ll, 28, 29 and 30 are preferably formed of non-magnetic material.

To provide for the turning of the flux-shunt ing member 23 above referred to, for purposes of shunting more or less of the magnetic flux between the pole-salients l3 and I on the one hand and the core 2! on the other hand, the said core is preferably mounted within the spool H) with freedom for rotat on therein. The rear face of the said flux-shunting member 23 is held in frictional engagement with the forward face of the mounting-plate IT by means of a concavoconvex spring-washer 3 l. y

The spring-washer 3| above referred to, has its outer edge pressing against the rear face of the end wall 52 of the shell Hi and has its central portion seated against the under face of the head of a retaining-screw 32 tightly threaded into the rear end of the core 2| so as to effectively become a part thereof for normal operating purposes.

In addition to serving to hold the flux-shunting member in engagement with the forward face of the mounting-plate ll, the spring-washer 3i and the retaining-screw 32 also serve to hold the respective forward faces of the shell and the spool [9 against the rear face of the mounting-plate IT.

The energizing-coil 20 may be supplied with alternating current from any suitable source such, for instance, as a source of 60-cycle 110-volt current, or the said energizing-coil may be supplied with interrupted direct current in any suitable manner such, for instance, as in the manner common in the art of bells and buzzers.

Preferably and as shown, the lower end of the flexible armature-arm 28 is provided with astriker 33 which is adapted to strikeanysuitableobject such, for instance, as a bell or gong.

The energization of the energizing-coil 20 will cause the pole-salients l3 and M of the shell ill to assume one polarity at a given instant, while the head 25 of the core 2! assumes an opposite polarity. The magnetic flux thus produced will flow through the armature 27 and will attract theisamew against the-tension of the'resilient armature-arm 28 and will cause the striker 33 to strike: any suitable object to produce the.

desired sound;

Asthearmature 21 is pulled inwardly as above describedxit will move into a position-slightly pastsa position wherein its front face becomes substantially fiush with the respective outer faces of-the'pole-salients l3 and i i and the head 25. The tendency of the armature 2! to continue its movement inwardly under the impetus imparted to 'itby the magnetic fiux. will be checked by the said magnetic flux Without requiring. a positive mechanical stop With its consequent noise which might interfere with the clarity of the desired signal and possibly cause ultimatedamage'toa clock mechanism.

As explained in my copending application previously identified, should the movement of the armature 21 be too violent or not sufiiciently violent-to meet the exigencies of a given. situation, the-fiux-shunting member 23 may be turned by rotatingthe retaining-screw 32,:to thus cause the said-member to shunt more or less of the magnetic flux between the pole-salients I3 and M on the one hand-and the core 2i on the other hand, thereby varying theamount of flux whichwill flow through thearmature 21.

By aperturing the armature 23 or its equivalent, and-utilizing the magnetic flux not only to move thesaid-armature but to check the movement thereof, a highly efiicient audible-signal device is provided which does not have its intended clarity of-signals interfered with by objectionable noises madeby'eiforts to mechanically check the movementof the armature.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments :are, therefore, to be considered in all respects' as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

' aim:

1." An electromagnetic audible-signal device, including in. combination: an energizing-coil; a magneticcore extending through the interior of the saidenergizing-coil and having a pole-salient adjacent one end projecting beyond the adjacent end of the saidenergizing-coil a distance materially greater than the thickness of the hereinaftermentioned' armature; a magnetic'shell extending over the'exterior of the said energizingcoil and provided at its end adjacent the polesalient of the said core with two pole-salients located substantially diametrically opposite each other on the respective opposite sides of the pole-salient of the said core and projecting beyond the adjacent end of the said energizingcoil a distance materially greater than the thicknessof the hereinafter-mentioned armature; and an armature having a substantially-central opening therethroughadapted to freely fit over the pole-salient of the said core, and the said armature being shaped and sized to freely fit between thetwo'saidpole-salients of the said shell and to vibrate therebetween Without striking any of the aforesaid pole-salients or the said energizingcoil.

2. An electromagnetic audible-signal device, including in combination: an energizing-coil; a magnetic core extending through the interior of the said energizing-coil and having a relativelyslender neck. adjacent one end and an overhanging head at the end of the said'neck projecting beyond the adjacent end of the said energizingcoil a distance materially greater than the thickness of the hereinafter-mentioned armature; a magnetic shell extending over the exterior of the said energizing-coil and provided at its end adjacent the head of the said core with a polesalient projecting beyond the adjacent end of the said. energizing-coil a distance 'materially greaterthan the thickness of the hereinaftermentioned armature; and-an armature having an. opening therethrough adapted to. freely; fit over the headof the saidcore and the said arma ture being shaped and sized tofreelyfit between the head of the said core and the pole-salient of;

the said shell andtovibrate therebetween without; striking anyofthe aforesaid pole-salientsor the :said energizing-coil.

3 An electromagneticv audible-signal device, includinglin combination: an energizing-coil;- a magnetic core extending through the interior of the saidenergizing-coil and having a relativelyslender neck adjacent one end and an overhanging head atvthe end of the said neck projectingbeyond the adjacent end ;of the said energizing-coil a distance materially greater than the thickness of the hereinafter-mentioned armature; a magnetic shell extending over the exterior of the said energizing-coil and provided at its end adjacent the head of the said core with two pole-salients locatedisubstantially diametrically opposite each othervon the respective. opposite sides of the head of the said core and projecting beyond the adjacent end of the said energizinge coil a distance materially greater than the thickness of the hereinafter-mentionad armature; and an armature having a'substantially-central opening therethr ough adapted to freely vfit over the head of "the said core and the said armature being shaped and sized to freely fit between the respective pole-salients of the said shell and .to vibrate therebetween without striking any of-the aforesaid pole-salients or the said energizing-coil.

4. An electromagnetic audible-signal device, including in combination: an energizing-coilf a magnetic core extending through the interior of the'said energizing-coil and having a pole-salient adjacent one end'projecting beyond the adjacent endof the said energizing-coil a distance materially greater than the thickness of the hereinafter-mentioned armature; a magneticshell extending over the exterior. ofv the said energizingcoil and. provided-at its-end adjacent the, polesalient of the said core with a pole-salient pro- ARTHUR B. POOLE.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Wahl Apr. 25, 1933 Morganstern Apr. 13, 19-37 FOREIGN PATENTS Country Date Great Britain Aug. 22, 1935 

